A group of four co-investigators and their research groups at Rutgers University and the University of Medicine and Dentistry of New Jersey operate a shared X-ray crystallographic facility. Edward Arnold, Helen Berman, Millie Georgiadis , and Ann Stock are studying crystallographic structures of proteins, nucleic acids, and protein-nucleic acid complexes that span a wide range of biomedically important systems. Funds are requested to purchase an image plate X-ray detector system that will complement the currently saturated data collection resources in the shared X-ray facility (consisting of a Xuong-Hamlin multiwire area detector system and a Rigaku R-Axix II image plate detector system). Over 30 scientists from the four major groups regularly use the shared facility and the structural projects involve collaborations with other highly productive biomedical researchers. The additional detector system requested, the Rigaku R-Axis IV image plate detector and scanner, would enhance the capabilities of the shared X-ray laboratory not only by increasing data collection access time for each of the groups, but also by permitting 1)collection of higher resolution data from both strongly and weakly diffracting crystals and 2) more efficient collection of data from crystals with large unit cells. Funds are also requested to purchase a liquid nitrogen crystal cryostat system and a computer workstation to upgrade the Xuong-Hamlin detector system to optimize its utility to the co-investigators. The outstanding support staff of the shared X-ray laboratory will assist in installation of the new instrument, training and maintenance, and continued operation of the facility. The sponsoring institutions (Rutgers University, the University of Medicine and Dentistry of New Jersey, the Center for Advanced Biotechnology and Medicine, and the Waksman Institute) have contributed seed funding ($40,000) for partial support of the capital costs and are committed to continuing to pay the operations and maintenance costs of the shared facility.